Comment 1 for bug 264104

It appears the problem was the driver was trying to scan for networks constantly, as well as Network Manager doing so, and the probes tripping each other up in the driver.

Adding:
options ipw2200 hwcrypto=1 associate=0 debug=0x43fff
(relevant part being associate=0)
to /etc/modprobe.d/ipw2200

seems to have fixed it.